1. Field of the Invention
The present invention relates to a synchronous controller for causing a slave axis (means for moving a slave element) to synchronously follow a master axis (means for moving a master element), and more particularly, to a synchronous controller in which an operation of a master axis is composed of operations of a plurality of axes.
2. Description of Related Art
As a method for moving a slave element to synchronously follow a motion of a master element as a reference element, there is known a method of controlling master and slave axes, these axes respectively serving as means for moving the master element and means for moving the slave element to synchronously follow the master element. This control method is referred to as electronic cam since it electrically achieves an operation equivalent to that of a cam and a cam follower which moves to follow rotation of the cam.
In the synchronous control of master and slave axes in which the master axis serves as means for moving a tool or the like, the motion of the master axis is determined as a combination of motions of a plurality of axes. For example, in a case where X and Y axes individually drive the tool to move in the perpendicular X- and Y-axis directions, a motion of the tool is realized by interpolation of the X and Y axes.
As for this kind of master axis serving as a driving mechanism for the tool, etc. and operated by interpolation of the plurality of axes, a control mode is conventionally adopted in which the master and slave axes are operated in synchronism with an imaginary axis which is provided upwardly to the master axis.
However, such synchronous control for master and slave axes using the imaginary axis is disadvantageous in that it requires two pairs of axes, i.e. the imaginary and master axes and the imaginary and slave axes, resulting in a more complicated arrangement than the basic arrangement only requiring one pair of axes, i.e. the master and slave axes. Furthermore, additional control for the imaginary axis makes the program and sequence complicated.
For the master axis control in which a combined motion of the plurality of axes is controlled by an external controller, there is not any method for synchronously controlling the master and slave axes using the imaginary axis.